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Friday, July 13, 2012

Laser light casts the first atomic shadow ever photographed.

Science and techno world topic: Technology

Technique might help turn atoms into vehicles for secret
messages

Image: courtesy Kielpinski Group, Griffith University

Scientists have taken the first ever snapshot of an
atom's shadow—the smallest ever photographed using visible light. The imaging
technique could have big implications for genetic research and cryptography,
researchers say.

The pioneering shutterbugs used an electrical field to
suspend a charged atom, or ion, of the element ytterbium in a vacuum chamber.
They then shot a laser beam—about a thousand times wider than the atom—at the
ytterbium.

The ytterbium atom absorbed a tiny portion of the light,
and the resulting shadow was magnified by a lens attached to a microscope, then
recorded via a digital camera sensor.

The team used ytterbium because they knew they could
create lasers of the right color to be strongly absorbed by the element.

"Each element responds to different specific
wavelengths ... so we would need different laser systems to use this technique
on a different atom," said study leader Dave Kielpinski. Atoms, he added,
are the smallest things that can be seen in visible light, and though the
team's shadow shots are unprecedented, atoms themselves have been photographed
before.

Since capturing the unique picture, the team has been
refining their technique, creating (as yet unreleased) photos of ytterbium
shadows twice as dark as in the above image, said Kielpinski, a physicist at
Australia's Griffith University.

The group is also working on increasing the resolution of
their images, so that it might one day be possible to see how the electrons
orbiting an atom affect the shape of its shadow.

Atomic Encryption

The shadow-imaging technique could one day enable
scientists to study DNA inside living cells by shining a laser at them and
observing patterns of light absorption, the researchers say. Current
techniques—involving attaching special molecules to DNA—are potentially harmful
to cells.

The technology might also one day be harnessed to send
information across "quantum cryptography networks," which would use
single atoms as data-storage devices and quantum physics to guarantee privacy,
Kielpinski said.

"Our work gives a new way to get light to talk to
single atoms," he added, "so we can cook up new protocols for these
storage nodes."

The atom-shadow research is detailed in the July 3 issue
of the journal Nature Communications.